Components

In the power management model, each device is composed of zero or more power-manageable components. If a device has no components, then the device is not power manageable.

Components correspond to parts of the device that can be put into a state that requires less power than normal. The definition of which components a device implements depends on the device driver writer, with one exception: component zero must represent all parts of the device that have hardware state that would be lost if power were to be completely removed from the device.